Overtime, bonuses, and supplemental withholding
Why lump-sum pay can look over-taxed, what flat supplemental withholding is doing, and how to reconcile withholding with your annual return.
Supplemental pay is still ordinary wages
Overtime, commissions, and many cash bonuses are wages. When you file, they generally stack into ordinary income with base salary. The sting is often in withholding timing: payroll must remit soon after payment, and IRS rules offer more than one withholding path.
Flat versus aggregate withholding
On identifiable supplemental payments, employers may withhold a flat federal amount on the supplemental portion when separated from regular wages—this is a payroll convenience, not your personalized marginal rate.
Translation
A big check can look “taxed at 40%” because federal, state, FICA, and locals stack—even if your annual average rate is lower.
Alternatively, employers can combine supplemental pay with regular wages and withhold using aggregate methods that annualize a spike—this can feel aggressive in the short run.
States and locals: verify, don’t generalize
States are not required to mimic federal supplemental methods. Cities with local earned-income taxes may add another layer on the same payment.
If something looks wildly wrong, open a payroll ticket with documentation—systems miscode jurisdictions after moves.
- Read state revenue guidance for supplemental wage withholding.
- Compare year-over-year local wage boxes after a relocation.
What to do next
Practical next steps based on this topic.
Treat large bonuses and overtime seasons as planning events. Adjust W-4 or estimates if refunds or balances swing wildly.
- Haircut the gross mentally: Assume meaningful withholding on bonuses; model net before spending.
- Revisit W-4 midyear: If OT or commissions are a large share of income, use the IRS estimator.
- Keep PDFs: Supplemental pay is where payroll errors show up first.